New Hampshire Code of Administrative Rules
Env - Department of Environmental Services
Subtitle Env-Ws - Division of Water
Chapter Env-Ws 300 - NEW HAMPSHIRE DRINKING WATER RULES
Part Env-Ws 380 - FILTRATION, DISINFECTION, TREATMENT PLANT AND WASTE RECYCLING
Section Env-Ws 380.27 - Additional Filtration Requirements for All Systems

Universal Citation: NH Admin Rules Env-Ws 380.27

Current through Register No. 13, March 27, 2025

(a) Pursuant to 40 CFR 141.502, beginning January 14, 2005,the owner of a public water system that does not meet all of the criteria for avoiding filtration shall provide:

(1) Treatment consisting of disinfection, as specified in Env-Ws 380.11; and

(2) Filtration treatment as specified Env-Ws 380.12.

(b) A water system using conventional filtration treatment or direct filtration shall achieve the following:

(1) The turbidity level of representative samples of the system's filtered water shall be less than or equal to 0.3 NTU in at least 95% of the measurements taken each month, measured in accordance with Env-Ws 380.13 and Env-Ws 380.19; and

(2) The turbidity level of representative samples of a system's filtered water shall not exceed 1 NTU, measured in accordance with Env-Ws 380.13 and Env-Ws 380.19.

(d) The owner of a water system using filtration treatment other than conventional filtration treatment, direct filtration, slow sand filtration, or diatomaceous earth filtration may submit a written request to the department to use a filtration treatment not listed in (b) above or in Env-Ws 380.12.

(e) The written request shall include:

(1) The system name;

(2) The system EPA number;

(3) A description of the proposed alternative filtration equipment, disinfection treatment, or both; and

(4) Pilot plant studies conducted to support the use of the proposed alternative treatment.

(f) The department shall respond to the request in writing and shall approve the request if:

(1) The proposed alternative treatment meets the requirements of Env-Ws 380.11; and

(2) The proposed alternative treatment consistently achieves the following:

a. Not less than 99.9% removal or inactivation of giardia lamblia cysts;

b. Not less than 99.99% removal or inactivation of viruses; and

c. Not less than 99% removal of cryptosporidium oocysts.

(g) After installation of treatment, the system shall meet the turbidity requirements specified in Env-Ws 380. 12(c).

(h) After installation of treatment, the water system shall consistently achieve the requirements in (g), above.

(i) In addition to monitoring required by Env-Ws 380.19, a public water system owner providing conventional filtration or direct filtration shall:

(1) Conduct continuous monitoring of turbidity for each individual filter using an approved method specified in Env-Ws 380.13; and

(2) Calibrate turbidimeters using the procedure specified by the manufacturer.

(j) A public water system owner shall record the results of individual filter monitoring every 15 minutes.

(k) A SW/GWUDISW system shall complete monthly reporting for individual filters and maintain records according to Env-Ws 380.28.

(l) If there is a failure in the continuous turbidity monitoring equipment, the system owner shall conduct grab sampling every 4 hours in lieu of continuous monitoring until the turbidimeter is repaired and back on-line.

(m) A system owner shall repair the monitoring equipment within:

(1) 5 business days of the failure if it serves at least 10,000; and

(2) 14 business days of the failure if it serves less than 10,000.

(n) If a system serving fewer than 10,000 people only consists of 2 or fewer filters, the system owner may conduct continuous monitoring of combined filter effluent turbidity in lieu of individual filter effluent turbidity monitoring. Continuous monitoring shall meet the same requirements set forth in (i) through (1) above.

#7754, eff 8-21-02; ss by #8352, eff 5-14-05 (formerly Env-Ws 380.29)

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